The efficiency of a fluid powered diaphragm pump is defined as a comparison of the ratio of the input fluid volume over the fluid inlet pressure consumed by the pump with the ratio of the output fluid volume over the system head generated by the pump. The efficiencies of currently-available pumps vary depending upon the operating parameters and operating conditions. While the input fluid pressure is a parameter that can be easily controlled, the input fluid volume is typically fixed and depends upon the design of the pilot valve assembly and the main fluid valve or main air valve assembly. In the event it is desired to adjust the input fluid volume to the main fluid valve, the pump would need to be disassembled and modifications would need to be made to the main valve and/or the pilot valve. Of course, this procedure is entirely too costly and time consuming to be implemented in practice.
Therefore, there is a need for an improved fluid powered diaphragm pump design whereby the flowrate or input flow volume to the main fluid valve can be adjusted without substantially disassembling the pump and/or replacing the main fluid valve.